<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>练习绘制风车与气泡</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .hello{
            height: 480px;
            width: 480px;
            margin: 0 auto;
            transition: 6s;
        }
        .hello > div{
            height: 200px;
            width: 200px;
            float: left;
            margin: 20px;
            background-color: #acf;

        }
        .hello div:nth-child(1),.hello div:nth-child(4){
            border-radius: 0 50%;
        }
        .hello div:nth-child(2),.hello div:nth-child(3){
            border-radius: 50% 0;
        }
        .hello:hover{
            transform: rotate(360deg);
        }
        .bubble{
            position: relative;
            left: 100px;
            top: 600px;
            width: 500px;
            height: 300px;
            border: 1px solid;
            border-radius: 50%; 
            text-align: center;
            line-height: 300px;
        }
        .bubble::after,
        .bubble::before{
            content: "";
            position: absolute;
            right: 0;
            bottom: 0;
            border: 1px solid;
            border-radius: 50%;
        }
        .bubble::before{
            width: 70px;
            height: 50px;
            bottom: -50px;
            right: -50px;
        }
        .bubble::after{
            width: 35px;
            height: 25px;
            bottom: -100px;
            right: -100px;
        }
    </style>
</head>
<body>
    <div class="hello">
        <div></div>
        <div></div>
        <div></div>
        <div></div>
    </div>
    <div class="bubble">6666666666666666666</div>
</body>
</html>